话题引入
- 在做一个BBS系统，这些信息里面是否包含脚本语言，敏感信息等，我们要把这些内容替换掉或者删掉。所以，要录入到数据库的信心都要，都要对其进行过滤。对于敏感信息的处理，我的做法是在网上找到一些敏感信息并建立数据库，然后以这个数据库为准，过滤掉敏感信息。
- 补充：去网上查一查极限编程资料。
package com.alan.chain.m1;
public class MessageProcessor {
private String msg;
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
// 现在的处理是，大而全的处理方法，违反了设计模式6原则中的单一职责原则。
public String process() {
// 返回处理后的字符串, 链式编程
String r = msg.replace("<", "[")
.replace(">", "]");
// 处理敏感字眼
r = r.replace("被就业", "就业")
.replace("敏感", "");
// ...
return r;
}
}
package com.alan.chain.m1;
public class Client {
public static void main(String[] args) {
String msg = "大家好:),<script>, 敏感，被就业，网络授课没感觉，因为看不见大伙儿";
MessageProcessor mp = new MessageProcessor();
mp.setMsg(msg);
String result = mp.process();
System.out.println(result);
}
}
- 上例子程序中的处理方式，大而全，即不满足设计模式6原则中的单一职责原则，又不满足开闭原则。那么如何解决这个问题，将耦合度高的内容变成耦合度较低的代码呢？（对消息进行过滤，而且过滤规则要进行动态的指定）由此引出下面的程序。
package com.alan.chain.m2;
public interface Filter {
// 对字符串进行过滤
String doFilter(String msg);
}
package com.alan.chain.m2;
public class HTMLFilter implements Filter {
public String doFilter(String msg) {
return msg.replace("<", "[")
.replace(">", "]");
}
}
package com.alan.chain.m2;
public class SensitiveFilter implements Filter {
public String doFilter(String msg) {
return msg.replace("被就业", "就业")
.replace("敏感", "");
}
}
package com.alan.chain.m1;
import com.alan.chain.m2.Filter;
import com.alan.chain.m2.HTMLFilter;
import com.alan.chain.m2.SensitiveFilter;
public class MessageProcessor {
private String msg;
private Filter[] filters = {new HTMLFilter(), new SensitiveFilter()};
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
public String process() {
// 返回处理后的字符串, 链式编程
String r = msg;
for (Filter f : filters) {
r = f.doFilter(r);
}
return r;
}
}
package com.alan.chain.m1;
public class Client {
public static void main(String[] args) {
String msg = "大家好:),<script>, 敏感，被就业，网络授课没感觉，因为看不见大伙儿";
MessageProcessor mp = new MessageProcessor();
mp.setMsg(msg);
String result = mp.process();
System.out.println(result);
}
}
- 这样做可以进行规则的排序，新的规则可以做扩展，如果哪个信息不需要了，直接给删掉就可以了。下一个版本要解决的问题就是，两个链条之间如何组合。
package com.alan.chain.m3;
public interface Filter {
// 对字符串进行过滤
String doFilter(String msg);
}
package com.alan.chain.m3;
import java.util.ArrayList;
import java.util.List;
public class FilterChain implements Filter {
private List<Filter> filters = new ArrayList<Filter>();
public FilterChain addFilter(Filter filter) {
// 将过滤器加入FilterChain中，将FilterChain返回
this.filters.add(filter);
return this;
}
public String doFilter(String msg) {
String result = msg;
for (Filter f : filters) {
result = f.doFilter(result);
}
return result;
}
}
package com.alan.chain.m3;
public class HTMLFilter implements Filter {
public String doFilter(String msg) {
return msg.replace("<", "[")
.replace(">", "]");
}
}
package com.alan.chain.m3;
public class SensitiveFilter implements Filter {
public String doFilter(String msg) {
return msg.replace("被就业", "就业")
.replace("敏感", "");
}
}
package com.alan.chain.m3;
public class MessageProcessor {
private String msg;
private FilterChain fc;
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
public FilterChain getFc() {
return fc;
}
public void setFc(FilterChain fc) {
this.fc = fc;
}
public String process() {
return fc.doFilter(msg);
}
}
package com.alan.chain.m3;
public class Client {
public static void main(String[] args) {
String msg = "大家好:),<script>, 敏感，被就业，网络授课没感觉，因为看不见大伙儿";
MessageProcessor mp = new MessageProcessor();
FilterChain filterChain = new FilterChain();
filterChain.addFilter(new HTMLFilter())
.addFilter(new SensitiveFilter());
FilterChain filterChain2 = new FilterChain();
filterChain2.addFilter(filterChain);
// 用Filter处理Msg
mp.setFc(filterChain2);
mp.setMsg(msg);
mp.process();
String result = filterChain.doFilter(msg);
System.out.println(result);
}
}
- 上面的代码中的MessageProcessor类可以删掉。将其内容整合到含有Main方法的类中。
package com.alan.chain.m4.web;
public interface Filter {
void doFilter(Request request, Response response);
}
package com.alan.chain.m4.web;
import java.util.ArrayList;
import java.util.List;
public class FilterChain implements Filter {
private List<Filter> filters = new ArrayList<Filter>();
public FilterChain addFilter(Filter filter) {
// 将过滤器加入FilterChain中，将FilterChain返回
this.filters.add(filter);
return this;
}
public void doFilter(Request request, Response response) {
for (Filter f : filters) {
f.doFilter(request, response);
}
}
}
package com.alan.chain.m4.web;
public class HTMLFilter implements Filter {
public void doFilter(Request request, Response response) {
request.requestStr = request.requestStr.replace("<", "[")
.replace(">", "]") + "---HTMLFilter";
response.responseStr = response.responseStr + "---HTMLFilter";
}
}
package com.alan.chain.m4.web;
public class SensitiveFilter implements Filter {
public void doFilter(Request request, Response response) {
request.requestStr = request.requestStr.replace("被就业", "就业")
.replace("敏感", "") + "---SensitiveFilter";
response.responseStr = response.responseStr + "---SensitiveFilter";
}
}
package com.alan.chain.m4.web;
public class Request {
String requestStr;
public String getRequestStr() {
return requestStr;
}
public void setRequestStr(String requestStr) {
this.requestStr = requestStr;
}
}
package com.alan.chain.m4.web;
public class Response {
String responseStr;
public String getResponseStr() {
return responseStr;
}
public void setResponseStr(String responseStr) {
this.responseStr = responseStr;
}
}
package com.alan.chain.m4.web;
public class Client {
public static void main(String[] args) {
String msg = "大家好:),<script>, 敏感，被就业，网络授课没感觉，因为看不见大伙儿";
Request request = new Request();
request.setRequestStr(msg);
Response response = new Response();
response.setResponseStr("response");
FilterChain fc = new FilterChain();
fc.addFilter(new HTMLFilter())
.addFilter(new SensitiveFilter());
fc.doFilter(request, response);
System.out.println(request.getRequestStr());
System.out.println(response.getResponseStr());
}
}
- 学习的捷径：先学脉络，后学细节
- 期望效果是对Request, Response进行处理，Request是正序，Response是倒序，上面例子中的效果是都是正序。那么如何来解决这个问题呢？请看下面的代码。
package com.alan.chain.m5.web;
public interface Filter {
void doFilter(Request request, Response response, FilterChain chain);
}
package com.alan.chain.m5.web;
import java.util.ArrayList;
import java.util.List;
public class FilterChain implements Filter {
private List<Filter> filters = new ArrayList<Filter>();
int index = 0;
public FilterChain addFilter(Filter filter) {
// 将过滤器加入FilterChain中，将FilterChain返回
this.filters.add(filter);
return this;
}
public void doFilter(Request request, Response response, FilterChain chain) {
if (index == filters.size())
return;
Filter f = filters.get(index ++);
f.doFilter(request, response, chain);
}
}
package com.alan.chain.m5.web;
public class HTMLFilter implements Filter {
public void doFilter(Request request, Response response, FilterChain chain) {
request.requestStr = request.requestStr.replace("<", "[")
.replace(">", "]") + "---HTMLFilter";
chain.doFilter(request, response, chain);
response.responseStr = response.responseStr + "---HTMLFilter";
}
}
package com.alan.chain.m5.web;
public class SensitiveFilter implements Filter {
public void doFilter(Request request, Response response, FilterChain chain) {
request.requestStr = request.requestStr.replace("被就业", "就业")
.replace("敏感", "") + "---SensitiveFilter";
chain.doFilter(request, response, chain);
response.responseStr = response.responseStr + "---SensitiveFilter";
}
}
package com.alan.chain.m5.web;
public class Request {
String requestStr;
public String getRequestStr() {
return requestStr;
}
public void setRequestStr(String requestStr) {
this.requestStr = requestStr;
}
}
package com.alan.chain.m5.web;
public class Response {
String responseStr;
public String getResponseStr() {
return responseStr;
}
public void setResponseStr(String responseStr) {
this.responseStr = responseStr;
}
}
package com.alan.chain.m5.web;
public class Client {
public static void main(String[] args) {
String msg = "大家好:),<script>, 敏感，被就业，网络授课没感觉，因为看不见大伙儿";
Request request = new Request();
request.setRequestStr(msg);
Response response = new Response();
response.setResponseStr("response");
FilterChain fc = new FilterChain();
fc.addFilter(new HTMLFilter())
.addFilter(new SensitiveFilter());
fc.doFilter(request, response, fc);
System.out.println(request.getRequestStr());
System.out.println(response.getResponseStr());
}
}
- 此时，如果有一个Request请求过来了，发现它不合乎条件，不合法，一发现它，停掉后续的处理不处理了。怎么做呢？
- 学习框架，先应用，然后再学习原理。学习框架，明白其思想。
- 应用驱动学习。
- 学习思想，学习设计方面的能力。
- 站在整体项目上的一个把握。少想一点，多做一点。
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